Air heater



FIG. 1 is a perspective view of an air heater showing my new design;

FIG. 2 is a front elevation view thereof on a reduced scale;

FIG. 3 is a rear elevation view thereof on a reduced scale;

FIG. 4 is a left side elevation view thereof on a reduced scale;

FIG. 5 is a right side elevation view thereof on a reduced scale;

FIG. 6 is a top plan view thereof on a reduced scale; and

FIG. 7 is a bottom plan view thereof on a reduced scale. 

The ornamental design for an air heater, as shown. 